Photogated Synaptic Transistors Based on the Heterostructure of 4H-SiC and Organic Semiconductors for Neuromorphic Ultraviolet Vision

Abstract

Neuromorphic vision that integrates the functionalities of sensing, memory, and processing may provide an important approach to overcome the drawbacks of a conventional artificial visual system such as data redundancy and high-power consumption. It has exhibited considerable potential to mimic the functionalities of human vision even beyond the visible-light range. In this work, we show an ultraviolet (UV)-responsive synaptic transistor based on the heterostructure of 4H-SiC and organic semiconductors. Benefiting from the heterostructure design and photogating effect, the nonvolatility of the synaptic transistor is achieved. Various biological synaptic functionalities are successfully mimicked by the synaptic transistor. The electrical energy consumption of the device per synaptic event is only 0.55 fJ, which is comparable to the energy consumption of a biological synapse. Furthermore, the dynamic learning and forgetting process of the image of a letter is simulated by using an array of the devices, demonstrating the potential of the UV-responsive synaptic devices for neuromorphic UV vision with the capability of the image recognition and memory.

Recent advances in fabrication and functions of neuromorphic system based on organic field effect transistor

“…Recently, the neuromorphic OFET device with heterostructure semiconductor materials has emerged, while single semiconductor material neuromorphic OFET devices always need a charge-storage layer or other functional layers between the insulating layer and channel layer. Noticeably, the heterostructure semiconductor materials always possess a heterointerface that promotes the separation of excitons [62][63][64][65][66][67][68][69][70][71][72][73][74]. Gao et al reported a P-type and N-type bulk heterostructure as the channel layer of the OFET device (figure 3(a)), which showed the different functions with different mixed ratios of N-type semiconductor to p-type materials [62].…”

“…Additionally, several workers reported the neuromorphic OFET device with layer heterostructure semiconductors, for example, Liu et al depicted a synaptic transistor with the semiconductor material of 4H-SiC and organic semiconductors for neuromorphic ultraviolet (UV) vision [68]. In this device, the n-type 4H-SiC semiconductor material was selected as the substrate and light-sensitive layer of OFET, while the p-type P3HT organic material was used as the channel layer.…”

Heterostructure-Based Optoelectronic Neuromorphic Devices

“…The negative photoconductance was used to optically demonstrate LTD of the device (Figure 1c) and synaptic image sensing of a handwritten digit which achieved 84% accuracy at its highest. A study by Liu et al in 2023 presented a photogated synaptic transistor for neuromorphic UV vision, using heterostructures of 4H-SiC and p-type organic semiconductors, including PVK and P3HT (Figure 1d) [81]. The main absorption of UV happens in the 4H-SiC layer, while PVK and P3HT serve as p-type channels due to their high hole mobility.…”

Transistor-Based Synaptic Devices for Neuromorphic Computing

“…Various synaptic functions, such as PPF and LTP, could be mimicked in this structure. Many synaptic devices have been investigated substantially and shown to mimic synaptic functions based on similar mechanisms [65][66][67][68]. It should be mentioned that charge-trap-flash-based synaptic transistors were successfully fabricated based on a silicon nitride film as the charge-trapping layer and a silicon film as the channel layer in transistor devices [69,70].…”